Problem: Simplify the expression. $(6z^{4}+5z^{2})(-5z^{4}+2z^{3})$
First use the distributive property. $ 6 z^4 (-5 z^4) + 6 z^4 (2 z^3) + 5 z^2 (-5 z^4) + 5 z^2 (2 z^3) $ Simplify. $-30z^{8}+12z^{7}-25z^{6}+10z^{5}$